The small intestine and its mesentery occupy a large volume and are widely distributed within the abdominal cavity, lacking strong protection, making them prone to injury. They account for about one-fourth of abdominal organ injuries and rank first among intra-abdominal organ injuries during wartime.

bubble_chart Pathogenesis

Blunt trauma occurs when the small intestine is compressed against the lumbar vertebrae by violent force, causing the intestinal contents to rapidly move upward and downward—reaching the ligament of Treitz above and the ileocecal valve below—forming a high-pressure closed-loop segment of the intestine. Perforations often occur within 70 cm of the upper or lower ends of the small intestine. Occasionally, due to indirect violence (such as falls from heights or sudden stops during rapid movement), the intestine undergoes severe shaking within the abdominal cavity due to inertia. Gas and liquid inside the intestine suddenly transfer to a specific segment of the intestinal loop, leading to a sharp increase in intraluminal pressure and resulting in intestinal rupture. A few cases are caused by excessive contraction of the abdominal muscles or iatrogenic factors.

bubble_chart Clinical Manifestations

The clinical manifestations of small intestine injury mainly depend on the extent of the injury and whether there is organ damage. The primary symptoms include peritonitis, while shock and toxic symptoms may not be obvious. Some patients may present with internal bleeding, especially when mesenteric vessel rupture occurs, leading to hemorrhagic shock.

bubble_chart Diagnosis

Diagnostic peritoneal lavage may yield digestive fluid or bloody fluid, making the diagnosis straightforward in most cases. Abdominal X-ray has limited value, with only a few cases showing subdiaphragmatic free air. Some cases of small intestine blunt injury may present with no obvious symptoms or signs early on (within 6 hours post-injury), making diagnosis difficult. Close observation is necessary, and peritoneal lavage can provide strong evidence.

Surgery should be performed immediately after diagnosis. If intra-abdominal bleeding is found, the first step is to explore the parenchymal organs and mesenteric vessels to locate the bleeding site and manage it as appropriate, followed by examination of the intestinal tract, starting from the ligament of Treitz and proceeding segment by segment. Small perforations located at the mesenteric border can sometimes be difficult to detect. The proximal and distal ends of the small intestine, segments with adhesions, and loops of intestine entering hernial sacs are prone to injury and should be given special attention. For perforations, gentle clamping can be applied initially to prevent further spillage of intestinal contents. After completing the full exploration of the small intestine, further management should be determined based on the findings.

The management of small intestine trauma depends on its severity and extent. Fresh perforations or linear lacerations at the wound edges can be repaired by suturing. Large defects in the intestinal wall, severe contusion leading to loss of viability, or multiple perforations in a segment of the intestine may require partial small intestine resection and anastomosis.

Mesenteric contusions or lacerations often result in severe bleeding or hematoma formation. Management includes achieving hemostasis and resecting any intestinal segments with compromised circulation due to the injury. Repairing mesenteric defects is essential to prevent internal herniation. Occasionally, injury to the main trunk of the mesenteric artery may require vascular repair or anastomosis to restore blood flow. Extensive small intestine resection should be avoided to prevent short bowel syndrome. The mesenteric venous collateral circulation is relatively abundant, and ligation of larger veins generally does not cause circulatory impairment, but caution is still advised.